High-resolution photoelectron spectroscopy analysis of sulfidation of brass at the rubber/brass interface

Semiconducting 2H-MoS 2 with high chemical stability is a promising alternative to the existing electrocatalysts for the hydrogen evolution reaction (HER); however, the HER performance largely suffers from the limited number of active S sites and low mobility for charge transport. In this work, we demonstrate that the limitations of 2H-MoS 2 for the HER can be overcome by forming hybrid structures with metallic nanowires. Taking the integration with Pd as a proofof-concept, we show with solid experimental evidence that the one-dimensional structure of metallic nanowires facilitates electron transport to active S sites, while the interfacial charge polarization between MoS 2 and Pd increases the electron density of the S sites for improved activity. As a result, the hybrid structure exhibits a current density of 122 mA·cm −2 at −300 mV versus RHE and a Tafel slope of 44 mV·decade −1 with excellent durability, well exceeding the performances of bare 2H-MoS 2 and metallic 1T-MoS 2 . This work provides insights into electrocatalyst design based on charge transport and polarization, which can be extended to other hybrid structures.

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“…1(d)). The lattice fringes with spacings of 0.23 and 0.62 nm in the core and shell regions can be attributed to (111) [16,17].…”

Section: Resultsmentioning

confidence: 99%

Maneuvering charge polarization and transport in 2H-MoS2 for enhanced electrocatalytic hydrogen evolution reaction

et al. 2016

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“…Notably, the PCC wire had large and more numerous voids in the subsurface. The presence of the voids is attributed to the corrosive sulfur that reacts with Cu to form a sulfide, and thus consumes the Cu atoms of the wire [15,16]. To understand the diffusion behavior of each atom, the depth profile of element distribution was obtained by AES, as shown in Figure 1c,d.…”

Section: Methodsmentioning

confidence: 99%

A Study of the Sulfidation Behavior on Palladium-Coated Copper Wire with a Flash-Gold Layer (PCA) after Wire Bonding

2019

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Palladium-coated copper wire with a flash-gold layer (PCA) is an oxidation-resistant fine wire that simultaneously has the properties of palladium-coated copper wire (PCC) and gold-coated copper wire. This research used an extreme sulfidation test to compare corrosion resistance between the PCC and PCA wires. In addition to closely examining the morphology of the wires, the internal matrix after the sulfidation test is also discussed. In doing so, the PCA wire was bonded onto the aluminum pads and the sulfidation test was conducted. Then, we observed its morphology and elemental distribution and found that the flash-gold layer of the PCA wire effectively enhanced resistance to sulfidation corrosion. Because the copper ball had an alloying effect on the ball bonding, it produced different shapes of sulfide after the sulfidation test. The degree of corrosion on the wedge bond was different because of the presence or absence of the coated layer. In contrast, the flash-gold layer of the PCA wire enhanced the bonding force and retained low resistance characteristics after the sulfidation test.

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“…To realize strong adhesion between steel and rubber, the compound with the high sulfur concentration (thus, the accelerator/sulfur ratio is lower than the conventional rubber [15]) is usually used. Since the present study was one of a series of our studies that verify steel-rubber adhesion properties [16][17][18], which were found to be largely influenced by the amount of sulfur accumulated at the steel/rubber interface, we examined in the present study kinetic behaviors of sulfur in the steel belt rubber. It is noted that rubber compounds used in other parts of the automotive tires have accelerator/sulfur ratios between 0.5 and 0.7 with 1 phr of an accelerator and 1.5-2 phr of sulfur.…”

Section: Methodsmentioning

confidence: 99%

“…The rubber compound examined in the present study has a very low accelerator/sulfur ratio (0.06), as described in the experimental section. Formulation is typical for the steel belt rubber in which the sulfur additives are used for both crosslink formation in the rubber compound and the formation of cupper sulfides as an adhesive agent between rubber and steel cords embedded in the steel belt [18]. To realize a strong rubber-steel adhesion, a sufficient amount of sulfur is required to be migrated from the rubber compound to the adhesion interface.…”

Section: -mentioning

confidence: 99%

Hard X-ray photoelectron spectroscopy study of thermal effect on chemical state of sulfur in rubber compound

Ozawa¹,

Kubo²,

Amino³

et al. 2019

Express Polym. Lett.

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Hard X-ray photoelectron spectroscopy (HAXPES) has been utilized to study chemical state and kinetics of sulfur species in a rubber compound by examining thermally induced changes of S 1s core-level spectra. Two peaks at 2470 and 2472 eV together with the 2479 eV peak from SO 4 2are resolved in the S 1s spectrum. As the rubber compound is heated at 374, 412, and 440 K, the former two peaks show different thermal behaviors; the peak at 2472 eV is swiftly decreased in its intensity with heating time because of thermal desorption of the sulfur species, whereas the intensity of the 2470 eV peak shows a slight increase especially in the surface region of the rubber compound. On the basis of these thermal behaviors, the peaks at 2470 and 2472 eV are, respectively, associated with S atoms bonded directly to the C atoms and those bonded only to other S atoms. An Arrhenius plot analysis of the 2470 eV peak intensity variation reveals that the S-C bond formation and scission reactions compete with each other with a slightly smaller activation energy in the bond formation than in the bond scission.

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High-resolution photoelectron spectroscopy analysis of sulfidation of brass at the rubber/brass interface

Cited by 25 publications

References 30 publications

Maneuvering charge polarization and transport in 2H-MoS2 for enhanced electrocatalytic hydrogen evolution reaction

Maneuvering charge polarization and transport in 2H-MoS2 for enhanced electrocatalytic hydrogen evolution reaction

A Study of the Sulfidation Behavior on Palladium-Coated Copper Wire with a Flash-Gold Layer (PCA) after Wire Bonding

Hard X-ray photoelectron spectroscopy study of thermal effect on chemical state of sulfur in rubber compound

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